Halogens, such as, chlorine and bromine compounds, are generally used to sanitize bather water in swimming pools, spas and the like. The control is accomplished by maintaining a concentration of the halogen in the amount of 0.5 to 3.0 ppm. However, it has been found that the halogens are extremely susceptible to degradation by ultraviolet rays of the sun, with the result that the residual concentration of the halogen is quickly depleted.
To reduce the consumption of the halogen, it has been proposed to add a small quantity of cyanuric acid to the water. By using a concentration of cyanuric acid in the range of 30 to 60 ppm, the rate of of the chlorine or bromine loss can be reduced by as much as 60% to 70%.
More recently, stabilized halogens have been utilized for sanitizing bather water, in which the chlorine or bromine is reacted with amino based compounds. As a result, stabilized chlorine compounds, such as trichloro-s-triazine-trione or sodium-dichloro-s-triazine-trione have seen wide use for sanitizing bather water.
As a consequence of the repetitive use of using the stabilized chlorine compounds for sanitizing bather water, the concentration of the cyanuric acid keeps increasing and can exceed the recommended maximum level of 150 ppm of cyanuric acid.
Until now, the only feasible manner of reducing the concentration of cyanuric acid, once it has increased to an unacceptable level, has been to drain all or a portion of the water of the pool or spa and to refill with fresh water. This process is time consuming and costly, and in some areas of the country, during periods of low water reserve, the filling of pools is not permitted.